<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script>
			//js中定义变量不严谨，相比java比较严谨
			var x = 10;var y = 20;
			console.log(x+y);
			console.log(x*y);
			console.log(x);
			var x = 100;//java中编译错误，变量名不能重复定义
			console.log(x);
			console.log(typeof(x));
			var x = 'abc';//类型可以改变
			console.log(x);
			console.log(typeof(x));
			
			
		</script>
	</body>
</html>
